In a typical cellular system, also referred to as a wireless communications network, wireless terminals, also known as mobile stations and/or user equipment units communicate via a Radio Access Network (RAN) to one or more core networks. The wireless terminals can be mobile stations or user equipment units such as mobile telephones also known as “cellular” telephones, and laptops with wireless capability, e.g., mobile termination, and thus can be, for example, portable, pocket, hand-held, computer-comprised, or car-mounted mobile devices which communicate voice and/or data with radio access network.
The radio access network covers a geographical area which is divided into cell areas, with each cell area being served by a base station, e.g., a Radio Base Station (RBS), which in some networks is also called “NodeB” or “B node” or “Evolved NodeB” or “eNodeB” or “eNB” and which in this document also is referred to as a base station. A cell is a geographical area where radio coverage is provided by the radio base station equipment at a base station site. Each cell is identified by an identity within the local radio area, which is broadcast in the cell. The base stations communicate over the air interface operating on radio frequencies with the user equipment units within range of the base stations.
In some versions of the radio access network, several base stations are typically connected, e.g., by landlines or microwave, to a Radio Network Controller (RNC). The radio network controller, also sometimes termed a Base Station Controller (BSC), supervises and coordinates various activities of the plural base stations connected thereto. The radio network controllers are typically connected to one or more core networks.
The Universal Mobile Telecommunications System (UMTS) is a third generation mobile communication system, which evolved from the Global System for Mobile Communications (GSM), and is intended to provide improved mobile communication services based on Wideband Code Division Multiple Access (WCDMA) access technology. UMTS Terrestrial Radio Access Network (UTRAN) is essentially a radio access network using wideband code division multiple access for user equipment units (UEs). The Third Generation Partnership Project (3GPP) has undertaken to evolve further the UTRAN and GSM based radio access network technologies. Long Term Evolution (LTE) together with Evolved Packet Core (EPC) is the newest addition to the 3GPP family.
In operation, a network may release assigned radio resources of a user equipment based on an inactivity in order to reduce resource usage. User inactivity is a certain time period, defined by the value of a “user inactivity” timer, in which no user plane packets, meaning payload or application level data, are exchanged between the user equipment and network. On the expiration of user inactivity timer, the network releases the radio access specific part of the associated Evolved Packet System (EPS) bearers to save resources in the radio access network and to reduce battery consumption in the user equipment and hence the user equipment is transferred to a state of lower activity where it cannot immediately transfer or receive user plane data, more commonly referred to as Idle mode. Once the user equipment is put in idle mode, the default radio bearer is torn down, for example, there is no Radio Resource Control (RRC) connection once the user enters idle mode. When the user comes out of idle mode, for example, due to traffic, paging, the expiry of timers, etc., the user equipment has to reestablish the RRC connection before the bearers may get reactivated.